The Truth Behind Eclipses (Vampires Not Included)

The word
"eclipse" means much more than the vampire and werewolf thriller set
to hit theaters on Wednesday. But "The Twilight Saga: Eclipse," the
latest film based on the popular vampire book series, is being released between
two of nature's real-life eclipses ? a recent partial lunar eclipse and a solar
eclipse coming on July 11.

The study of
eclipses has been a part of astronomy since its inception, since they are some
of nature's most dramatic celestial shows.

The first lunar
eclipse of 2010 occurred on Saturday, June 26, and was visible across parts of
the Americas, the Pacific Ocean and eastern Asia. However, it was only a
partial eclipse
of the moon as it passed through part of Earth's shadow.

On July 11,
the second solar eclipse of 2010 will occur, creating a total eclipse along a
narrow corridor of the Earth's southern hemisphere.

Solar
eclipses occur when the Earth, moon and sun are aligned on the same plane, and
the moon comes between the Earth and the sun. [Solar
eclipse photos.]

A lunar
eclipse, on the other hand, occurs when the moon slips behind the Earth, which
blocks the sun's rays from striking the moon. With a lunar eclipse, the moon,
Earth and sun are again aligned (or closely so), with the Earth in the middle.

Mechanics
of the moon, sun and Earth

The type and
length of an eclipse depend upon the moon's location relative to its orbital
nodes, which are the points where the moon crosses the sun's apparent path in
the sky, explained NASA solar astronomer Mitzi Adams of the Marshall Space
Flight Center in Huntsville, Ala.? A lunar eclipse typically lasts for a few
hours, unlike a total solar eclipse, which usually lasts for only a few minutes,
she added.

The longest
total solar eclipse lasted about seven minutes, Adams said in a recent NASA
webchat.

However, the
first solar eclipse of 2010 ? the Jan. 15 annular
solar eclipse ? did last longer, but was not total. That annular solar
eclipse, in which the moon covers only a large portion of the sun, lasted over
eight minutes over some parts of Asia.

Looking at a
solar eclipse through a telescope, however, can be dangerous, Adams said.

"You
have to have a proper filter," she added. "The safest way is through
a method called projection, where you actually take the eyepiece out and
project the image onto a sheet of paper behind the telescope, without looking
at the sun. You move the sheet of paper back and forth until you get a focused
image."

While skywatchers
can expect the next solar eclipse on July 11, the next lunar eclipse won't occur
until Dec. 21. That lunar eclipse should be visible across the U.S., and, while
lunar eclipses can be viewed with a telescope, Adams says that it is not
necessary.

"Looking
at a lunar eclipse with a telescope is safe, but you don't really need a
telescope ? your eyes are better instruments in this case," Adams said.
"One could walk into the back yard to see it, assuming there are no
clouds. No telescope is required. Lunar eclipses are best viewed with the
unaided eye. However, while the eclipse is going on, you could use a telescope
to look at the craters and mountains on the moon."

Adams said
that while a lunar eclipse should be easily visible anywhere in the night sky,
the ideal location would be dark and away from city lights.

And all this
can be seen without the hassle of ticket lines, overpriced popcorn, or any price of
admission. All you have to do is know when to look up.